docs: def tiles(self, uid, z, x, y=None):
          """
          Return tiles from the specified dataset (uid) at
          the given position (z,x,[u])
          """
          tile_id = "{uid}.{z}.{x}".format(uid=uid, z=z, x=x)
          if y is not None:
              tile_id += ".{y}".format(y=y)
          url = "http://{host}:{port}/api/v1/tiles/?d={tile_id}".format(
              host=self.host, port=self.port, tile_id=tile_id
          )
  
          print("url:", url)
  
          req = requests.get(url)
          if req.status_code != 200:
              raise ServerError("Error fetching tile:", req.content)
  
          content = json.loads(req.content)
          return content[tile_id]